Gas company memo said valves of little value

FILE - In this Sept. 13, 2010, file photo, a man walks past the remains of homes damaged from a fire caused by an explosion in a mostly residential area in San Bruno, Calif. The National Transportation Safety Board's investigation has raised questions about whether the company should have known it was putting public safety at risk. Eight officials with the Pacific Gas and Electric Co. are scheduled to testify Tuesday, Mach 1, 2011, at a public hearing in Washington. (AP Photo/Jeff Chiu, File)
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FILE - In this Sept. 13, 2010, file photo, a man walks past the remains of homes damaged from a fire caused by an explosion in a mostly residential area in San Bruno, Calif. The National Transportation Safety Board's investigation has raised questions about whether the company should have known it was putting public safety at risk. Eight officials with the Pacific Gas and Electric Co. are scheduled to testify Tuesday, Mach 1, 2011, at a public hearing in Washington. (AP Photo/Jeff Chiu, File)
/ AP

National Transportation Safety Board chairman Deborah Hersman, left, listens as board member Robert Sumwalt questions PG&E employees during a hearing in Washington, Tuesday, March 1, 2011, to gather additional factual information for the ongoing investigation into the natural gas pipeline rupture and explosion in San Bruno, Calif., last year(AP Photo/Cliff Owen)— AP

National Transportation Safety Board chairman Deborah Hersman, left, listens as board member Robert Sumwalt questions PG&E employees during a hearing in Washington, Tuesday, March 1, 2011, to gather additional factual information for the ongoing investigation into the natural gas pipeline rupture and explosion in San Bruno, Calif., last year(AP Photo/Cliff Owen)
/ AP

WASHINGTON 
Officials for a California gas company involved in a deadly pipeline explosion last September acknowledged Tuesday that four years before the accident they rejected installing valves that could have automatically shut off or remotely controlled the flow of gas.

Pacific Gas and Electric Co. employees were questioned at a National Transportation Safety Board hearing about a 2006 memo that said installing the valves would have "little or no effect on increasing human safety or protecting properties."

Gas engineer Chih-hung Lee, author of the memo, said he considered only industry studies, not government studies, in reaching his conclusions. Industry studies, he said, found that most of the damage in gas pipeline accidents occurs in the first 30 seconds.

However, when the pipeline ruptured on Sept. 9 underneath a suburban San Francisco subdivision, gas continued to feed a pillar of fire for an hour and a half before workers could manually shut off the flow. Eight people were killed, many more injured and dozens of homes destroyed.

Investigators pointed to a 1999 Transportation Department study that warned that there is a significant safety risk as long as gas was being supplied to the rupture site and operators lacked the ability to quickly close manual valves.

"Any fire would have greater intensity and would have greater potential for damaging surrounding infrastructure if it is constantly replenished with gas," the government study said. "The degree of disruption in heavily populated and commercial areas would be in direct proportion to the duration of the fire."

Coroner's reports indicate at least five of the people killed in San Bruno were trying to flee when they died.

Keith Slibasager, PG&E's manager of gas system operations, said it took control room employees about 15 minutes following the explosion to figure out what had happened and would have taken about another 15 minutes to shut off the gas using automatic or remotely controlled valves. That's an hour less than it took in San Bruno.

Instead, about 12 minutes after the explosion, PG&E's dispatch center sent an off-duty employee to investigate the reported explosion, but he wasn't qualified to operate the manual valves needed to shut off gas feeding a huge fire that consumed homes, the safety board investigator Ravi Chhatre said.

It took 30 minutes after the rupture for the company to dispatch a crew capable of isolating the pipeline and 90 minutes for them to crank the valves shut, stopping all gas, he said.

PG&E officials acknowledged that after Lee's memo they made no effort to further explore the valves. They said that since the disaster, the company has begun a pilot project to install a dozen of the valves this year and study their effectiveness.

PG&E "is committed to expanding the use of these valves where appropriate and is working with industry experts to study the best use of those valves," the company said in a statement distributed during the hearing.

But Slibasager said there are potential safety drawbacks to the valves. When closed, they could cause widespread gas outages in the region that would put out pilot lights in homes and other buildings, he said. That poses the risk that when gas is turned back on, it could build up in buildings in which pilot lights are not relit right away, he said.